Coexistence of antiferromagnetic and ferromagnetic in Mn-doped anatase TiO₂ nanowires

Abstract

A series of Mn-doped TiO₂ nanowires (NWs) were prepared by hydrothermal method at the mole fraction of Mn changing from 0 to 12.0%. X-ray powder diffraction (XRD) analysis shows that all the samples have pure anatase structure. SEM and TEM studies show that the diameter and the length of the Mn-doped TiO₂ NWs are larger than those of the undoped TiO₂ NWs. Energy dispersive X-ray spectroscopy (EDX) reveals that the samples are composed of Ti, Mn and O. According to magnetization measurements, all samples show ferromagnetic behavior, but only the undoped TiO₂ NWs are completely ferromagnetic with a saturated magnetization about 1.0 mA·m²/kg. Mn-doped TiO₂ samples exhibit antiferromagnetic and ferromagnetic (AF-FM) behaviors simultaneously. Photoluminescence (PL) spectra demonstrate the existence of MnO₂ sublattice. These observations indicate that an AF-WF crossover is induced by the coexistence of TiO₂ sublattice and MnO₂ sublattice.

Keywords

TiO₂ / nanowires / Mn / antiferromagnetism / ferromagnetism

References

[1] MatsumotoY., MurakamiM., ShonoT., HasegawaT., FukumuraT.. Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide [J]. Science, 2001, 291(5505): 854-856

[2] AsahiR., TagaY., MannstadtW., FreemanA. J.. Electronic and optical properties of anatase TiO₂ [J]. Physical Review B, 2000, 61(11): 7459-7465

[3] WangZ. J., TangJ. K., ChenY. X., LeonardS., ZhouW. L., TungL. D.. Room-temperature ferromagnetism in manganese doped reduced rutile titanium dioxide thin films [J]. Journal of Applied Physics, 2004, 95(11): 7384-7386

[4] TorresC. E. R., GolmarF., CabreraA. F., ErricoL., NavarroM., RenteriaA. M. M., SanchezF. H., DuhaldeS.. Magnetic and structural study of Cu-doped TiO2 thin films [J]. Applied Surface Science, 2007, 254(1): 365-367

[5] YamauraK., WangX. H., LiJ. G., IshigakiT., Takayama-MuromachiE.. Magnetic properties of the highly iron-doped rutile TiO₂ nano crystals [J]. Materials Research Bulletin, 2006, 41(11): 2080-2087

[6] ErricoL. A., WeissmannM., RenteriaM.. Ab initio study of the magnetic ordering in the semiconductors Mn_xTi_1−xO₂, Co_xTi_1−xO₂ and Fe_xTi_1−xO₂ [J]. Physica B: Condensed Matter, 2004, 354(1/4): 338-340

[7] WangZ. J., WangW. D., TangJ. K., LuagL. D., LeonardS., ZhouW. L.. Extraordinary Hall effect and ferromagnetism in Fe-doped reduced rutile [J]. Applied Physics Letters, 2003, 83(3): 518-520

[8] HongN. H., SakaiJ., RuyterA., BrizeV.. Does Mn doping play any key role in tailoring the ferromagnetic ordering of TiO₂ thin films? [J]. Applied Physics Letters, 2006, 89(25): 252504

[9] KundysB., MaignanA., MartinC., NguyenN., SimonC.. Magnetic field induced ferroelectric loop in Bi_0.75Sr_0.25FeO_3−δ [J]. Applied Physics Letters, 2008, 92(11): 112905

[10] DormannJ. L., NoguesM.. Magnetic structures in substituted ferrites [J]. Journal of Physics: Condensed Matter, 1990, 2(5): 1223-1237

[11] KaminskiA., Das-SarmaS.. Polaron percolation in diluted magnetic semiconductors [J]. Physics Review Letters, 2002, 88(24): 247202

[12] LiuB.-s., WenL.-p., ZhaoX.-jian.. The photoluminescence spectroscopic study of anatase TiO2 prepared by magnetron sputtering [J]. Materials Chemistry and Physics, 2007, 106(2/3): 350-353

[13] WunderlichW., MiaoL., TanemuraM., JinP., KanekoK., TeraiA., Nabatova-CabinN., BelkadaR.. Ab-initio calculations of the optical band gap of TiO₂ thin films [J]. International Journal of Nanoscience, 2004, 3(4/5): 439-445

[14] PalominoM. R., TorresK. J., LozadaM. R., PortilloM. O., GarciaR. M., ZelayaA. O.. Photoluminescence of Rhodamine 6G-doped amorphous TiO₂ thin films grown by sol-gel [J]. Vacuum, 2007, 81(11/12): 1480-1483

[15] LeiY., ZhangL. D., MengG. W., LiG. H., ZhangX. Y., LiangC. H., ChenW., WangS. X.. Preparation and photoluminescence of highly ordered TiO₂ nanowire arrays [J]. Applied Physics Letters, 2001, 78(8): 1125-1127